1. Field of the Invention
This invention relates to novel cephalosporin compounds and the pharmaceutically acceptable salts thereof.
2. Description of the Prior Art
Most antibiotic compounds of penicillin and cephalosporin which have been actually used as a drug for remedy or prevention of infectious disease have a superior antibacterial activity but have little oral activity. Therefore, in the medical treatment by administering these drugs to patients, a trained medical expert has been required. Accordingly, development of cephalosporin antibiotic which can be orally administered and has strong antibacterial activities has been greatly desired, and many studies have been done for a long period of time. Of cephalosporin antibiotic compounds, only compounds having a specific structure such as cephalexin and its analogue have been actually used.
Most studies meeting the above described purpose relate to render the 4-position carboxylic acid group of cephalosporin compounds lipo-soluble to give the lipo-soluble cephalosporin derivatives such as the acetoxymethyl ester derivatives, the pivaloyloxymethyl ester derivatives and the methoxymethyl ester derivatives. However, these cephalosporin derivatives have not been put to practical use because of their low intestinal absorbability.
The inventors of this invention found that the intestinal absorption of the cephalosporin derivatives could be accelerated by bonding an oligopeptide with the cephalosporin derivatives. Thereafter, the inventors continued the study to provide novel cephalosporin compounds having the intestinal absorbability.